The Power Management Unit (PMU) is a
microcontroller
A microcontroller (MC, uC, or μC) or microcontroller unit (MCU) is a small computer on a single integrated circuit. A microcontroller contains one or more CPUs (processor cores) along with memory and programmable input/output peripherals. Pro ...
that governs
power functions of digital platforms. This
microchip
An integrated circuit (IC), also known as a microchip or simply chip, is a set of electronic circuits, consisting of various electronic components (such as transistors, resistors, and capacitors) and their interconnections. These components a ...
has many similar components to the average
computer
A computer is a machine that can be Computer programming, programmed to automatically Execution (computing), carry out sequences of arithmetic or logical operations (''computation''). Modern digital electronic computers can perform generic set ...
, including
firmware
In computing
Computing is any goal-oriented activity requiring, benefiting from, or creating computer, computing machinery. It includes the study and experimentation of algorithmic processes, and the development of both computer hardware, h ...
and
software
Software consists of computer programs that instruct the Execution (computing), execution of a computer. Software also includes design documents and specifications.
The history of software is closely tied to the development of digital comput ...
,
memory
Memory is the faculty of the mind by which data or information is encoded, stored, and retrieved when needed. It is the retention of information over time for the purpose of influencing future action. If past events could not be remembe ...
, a
CPU, input/output functions, timers to measure intervals of time, and
analog to
digital
Digital usually refers to something using discrete digits, often binary digits.
Businesses
*Digital bank, a form of financial institution
*Digital Equipment Corporation (DEC) or Digital, a computer company
*Digital Research (DR or DRI), a software ...
converters to measure the voltages of the main battery or power source of the computer. The PMU is one of the few items to remain active even when the computer is completely shut down, powered by the backup battery.
For portable computers, the PMU is responsible for coordinating many functions, including:
*Monitoring power connections and battery charges
*Charging
batteries when necessary
*Controlling power to other
integrated circuit
An integrated circuit (IC), also known as a microchip or simply chip, is a set of electronic circuits, consisting of various electronic components (such as transistors, resistors, and capacitors) and their interconnections. These components a ...
s
*Shutting down unnecessary system components when they are left idle
*Controlling sleep and power functions (On and Off)
*Managing the interface for built in keypad and touchpads on portable computers
*Regulating the
real-time clock (RTC)
See also
*
Power management integrated circuit (PMIC)
*
System Management Unit (SMU)
*
System Management Controller (SMC)
References
*"Desktop and Portable Systems: Second Edition" Edited by Owen W. Linzmayer. {{ISBN, 0-321-33546-5.
External links
Resetting the PMU on Macbook and MacbookPro computers– contains general information on the PMU
Apple Inc. hardware
Macintosh computers